JP2621743B2 - Colored polyethylene coating with excellent weather resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is a surface of a base material such as steel, weathering antidegradants color pigments and various polyethylene is coated with the colored polyethylene resin composition was prepared, excellent weather colored It relates to a polyethylene coating material.

[0002]

2. Description of the Related Art Steel materials used for a long time outdoors may be exposed to a severely corrosive environment. For example, steel sheet piles and steel pipe sheet piles are continuously driven into the ground to form protective fences, mainly for the protection of rivers, coasts, ports, etc., and steel pipe piles are used for foundations of offshore structures. Has been used for Also, steel pipes are sometimes used in corrosive environments as gas pipes or water pipes.

[0003] These steel materials are used in outdoor natural environments.
It is exposed to water such as river water, drainage water, rainwater, seawater, the atmosphere, sunlight, etc., and is in direct contact with earth, sand, mud, rubble, etc., so it is highly susceptible to corrosion. Therefore, long term (about
(40 years) effective anticorrosion measures were desired.

In recent years, as a countermeasure against this, a resin has
Heavy-corrosion-coated steel materials that have been provided with excellent corrosion resistance by coating with a thickness of 3 mm) are being used. Polyethylene resin is often used as a coating resin for the heavy corrosion-resistant coated steel material.

[0005] However, polyethylene resins are liable to deteriorate under the influence of ultraviolet rays contained in sunlight, and when used outdoors such as heavy anticorrosion coatings, carbon black is used for 1-3 times.
It was common to improve the weather resistance by adding about weight%, and the color tone was limited to black. However, in places where the living environment and natural environment should be maintained comfortably and neatly, it is necessary to color steel sheet piles and steel pipe sheet piles in colors that match the environment.Therefore, carbon black is used as the polyethylene resin for coating. It is desired to take measures against UV degradation without blending.

As a measure against such ultraviolet ray deterioration, in addition to the coloring pigment, a substance (ultraviolet ray absorber) which absorbs ultraviolet rays represented by a benzotriazole-based compound and converts it to low energy (a hindered amine-based substance generally abbreviated as HALS) Attempts have been made to incorporate a light stabilizer, an antioxidant such as a hindered phenol compound or a sulfur compound into a polyethylene resin. In the present specification, an ultraviolet absorber, a light stabilizer, and an antioxidant are hereinafter collectively referred to as a deterioration inhibitor.

As a method of adding these deterioration inhibitors, a method of adding an ultraviolet absorber only to the surface of a resin (Japanese Patent Laid-Open No.
JP-A-202836) and a method of adding an ultraviolet absorber and a phenolic antioxidant to the whole resin (JP-B-63-60712) are known.

[0008]

However, these deterioration inhibitors are expensive and cost several tens of times as much as the polyethylene resin used as a base, and the addition of a large amount thereof causes an increase in product cost. In particular, in the outer coating of outdoor piping such as gas pipes and water pipes, and in heavy corrosion protection coatings such as steel pipe piles, steel sheet piles and steel pipe sheet piles, it is necessary to add a large amount of an antioxidant, and the design of adding an excessive deterioration inhibitor is necessary. Can hurt the economics of the product.

Further, as described in JP-B-63-60712, even when a combination of an ultraviolet absorber and a phenolic antioxidant is blended into a polyethylene resin, the weather resistance of the resin is about 15 years.
(Sunshine weather meter black panel 30 at 63 ℃
00 hours), which was still insufficient to obtain a long-term weather resistance of about 40 years.

In the present invention, a steel material such as a steel sheet pile, a steel pipe sheet pile, a steel pipe pile, a steel pipe or the like is blended with a minimum deterioration preventing agent without impairing the economic efficiency and without adding carbon black. An object of the present invention is to provide a colored polyethylene resin coating material having excellent weather resistance, which is provided with long-term weather resistance of at least about 40 years by coating with a colored polyethylene resin layer of an arbitrary color.

[0011]

Means for Solving the Problems The present inventors have examined the weather resistance of a polyethylene resin by blending a coloring pigment and various kinds of deterioration inhibitors. One-sided hindered phenolic antioxidant to capture radicals, sulfur-based antioxidant to decompose and stabilize unstable peroxide generated at that time,
Two types of piperidine-based HAL exhibiting excellent light stabilizing action
It has been found that excellent long-term weather resistance of about 40 years can be achieved without adding carbon black by adding a certain amount or more of S and further an ultraviolet absorber to polyethylene, respectively.

Here, the present invention relates to polyethylene resin 100
One part hindered phenolic antioxidant per part by weight
0.05 parts by weight or more, a sulfur-based antioxidant having an ester bond is used in an amount of 30% to 70% of the amount of one-sided hindered phenolic antioxidant, and a hindered piperidine-based light stabilizer having a molecular weight of 600 or less 0.05% by weight or more, molecular weight Hindered piperidine-based light stabilizer of 1000 or more 0.05 parts by weight or more, UV absorber 0.
The gist of the present invention is a colored polyethylene coating material, characterized in that a resin layer composed of a colored polyethylene composition containing not less than 05 parts by weight is coated on the surface.

[0013]

The operation of the present invention will be described in detail below together with the structure. In the present invention, the base material to which the polyethylene resin coating is applied is generally a steel material, but the material of the base material is not limited to iron and steel, other metal materials such as aluminum, further stone materials, wood, Ceramics and the like are also possible. Hereinafter, a case will be described in which a steel material, which is a typical base material, is used as a base material.

The shape of the steel material (base material) is not particularly limited, and may be a tubular material such as a steel pipe, a steel pipe pile, a steel sheet pile, a sheet material such as a steel sheet pile, a rod material, a deformed material, or the like. Steel materials are prepared by physical means such as shot blasting, pickling,
It is preferable to clean the surface by appropriately combining chemical means such as alkali degreasing. Further, the steel material may be subjected to an appropriate base treatment such as plating and / or chemical conversion treatment (eg, chromate treatment, zinc phosphate treatment). In order to enhance the adhesion to the polyethylene resin layer, a coating pretreatment such as applying an appropriate primer such as an epoxy resin to the surface of the steel material and curing by baking drying or ultraviolet irradiation is required before coating the polyethylene resin. Can be carried out in the same manner as in the prior art.

The thickness of the polyethylene resin coating layer is selected according to the desired degree of corrosion protection. In case of heavy corrosion protection
In order to realize long-term weather resistance of about 0.5 to 5 mm, particularly about 40 years, it is preferably about 2 to 3 mm. In addition, since polyethylene resin has relatively low adhesiveness, a thin resin layer (for example, a maleic anhydride-modified polyethylene resin layer) for imparting adhesiveness, as is well known, is used to enhance the adhesiveness to steel. Preferably, it is present at the interface between the steel material and the resin coating layer.

The polyethylene resin used to form the coating layer may be either a homopolymer of ethylene or a copolymer of ethylene with a small amount of another olefin or vinyl monomer (eg, acrylic acid). .

As a deterioration inhibitor that can be added to the polyethylene resin coating, a radical chain inhibitor that captures active radical species generated in the deterioration process has been used as a hindered amine such as a phenol derivative, an aromatic amine derivative, or a piperidine derivative. Light stabilizers (HALS), etc .; sulfur compounds as peroxide decomposers that decompose unstable peroxides into stable compounds and prevent the progress of autoxidation,
Phosphorus compounds, organometallic compounds, etc .; and ultraviolet absorption that absorbs ultraviolet light, converts the absorbed light energy into harmless forms such as heat, and prevents incident light from reaching the chromophore where degradation starts. Benzotriazole compounds, benzophenone compounds, benzoate compounds,
Cyanoacrylate compounds and the like are known.

In the present invention, among these, in order to scavenge active radicals generated in the process of deterioration by ultraviolet rays, the antioxidant of one-sided hindered phenol and the ability to decompose and stabilize unstable peroxides are provided. Two types of hindered piperidines as HALS exhibiting an excellent light stabilizing action, an excellent sulfur-based antioxidant, and an ultraviolet absorber were each contained in the polyethylene resin coating in a certain amount or more.

As an optional additive, both hindered phenolic antioxidants having a function of scavenging radicals may be further added to the polyethylene resin coating for the purpose of maintaining heat resistance during processing.

In order to provide long-term weather resistance of about 40 years, a half-hindered phenolic antioxidant is added in an amount of 0.05 part by weight or more and a sulfur-based antioxidant having an ester bond to one-hundred parts by weight of polyethylene. 30% or more and 70% or less of the amount of the phenolic antioxidant, a hindered piperidine light stabilizer having a molecular weight of 600 or less of 0.05 part by weight or more, a hindered piperidine light stabilizer having a molecular weight of 1000 or more of 0.05 part by weight or more,
A polyethylene resin composition containing at least 0.05 part by weight of an ultraviolet absorber is used for forming a resin coating layer. By adding these deterioration inhibitors to the polyethylene resin at the same time, a large synergistic effect can be obtained with respect to the improvement of the weather resistance although the total amount of the deterioration inhibitors is small.
If the addition of any one of the components is omitted, or if the amount of the one component is less than a predetermined ratio, the synergistic effect is not effectively exhibited, and the weather resistance is reduced.

In the present invention, the reason why the single-sided hindered phenol-based antioxidant and the sulfur-based antioxidant having an ester bond are added together is that simultaneous addition of both produces an excellent synergistic effect, This is because the weather resistance can be improved. That is, since a hydrogen bond is generated between the hydroxyl group of the one-sided hindered phenolic antioxidant and the ester group of the sulfur-based antioxidant, both are present in close proximity. In the deterioration prevention process, phenolic antioxidants donate hydrogen to active radicals and prevent the deterioration by converting the radicals to peroxides, but the generated peroxide is unstable and decomposes into radicals, It becomes a new deterioration factor. At this time, since the sulfur-based antioxidant present in the vicinity reduces the peroxide generated by the deterioration prevention and continuously changes it to a stable compound, it is possible to achieve the prevention of the deterioration very effectively. Can be. At this time, if both hindered phenolic antioxidants are used instead of the single hindered phenolic antioxidants, the steric hindrance will hinder the hydrogen bond between the phenolic hydroxyl group and the ester group of the sulfur-based antioxidant. As a result, they are separated from each other, and the synergistic effect for preventing deterioration is reduced.

Here, the one-sided hindered phenolic antioxidant is a sterically hindered substituent such as a t-butyl group bonded to only one of the adjacent positions (ortho positions) on both sides of the phenolic hydroxyl group. It was done. In contrast,
Both hindered phenolic antioxidants are those in which sterically hindered substituents are bonded at adjacent positions on both sides of the phenolic hydroxyl group.

As the one-sided hindered phenol-based antioxidant, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy}-
1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 4,4′-thiobis (3-methyl-6
t-butylphenol), 1,1,3-tris (2-methyl-
4-hydroxy-5-t-butylphenyl) butane, triethylene glycol-bis- [3- (3-t-butyl-5
-Methyl-4-hydroxyphenyl) propionate]
And the like, but are not limited thereto.

Examples of sulfur-based antioxidants having an ester bond include pentaerythritol-tetrakis (β-
Lauryl-thiopropionate), distearyl-3,3 '
-Thiodipropionate, dilauryl-3,3'-thiodipropionate and the like, but are not limited thereto.

The sulfur-based antioxidant has an antagonistic effect with the hindered piperidine-based light stabilizer, which is HALS.
It is not preferred that there be a large amount of freely movable sulfur antioxidants. Therefore, the amount of the sulfur-based antioxidant added is limited to 30% or more and 70% or less of the one-sided hindered phenol-based antioxidant. If this amount is less than 30%, the above-mentioned synergistic effect will not be sufficiently exerted, and if it exceeds 70%, the free-moving sulfur-based antioxidant which does not form hydrogen bonds with the single-sided hindered phenol-based antioxidant. The amount increases, and it becomes difficult to expect improvement in deterioration prevention performance due to antagonism with HALS.

The reason why the addition amount of the one-sided hindered phenolic antioxidant is set to 0.05 part by weight or more with respect to 100 parts by weight of the polyethylene resin is that if it is less than 0.05 part by weight, the effect of preventing deterioration becomes small.

In the present invention, two kinds of hindered piperidine-based light stabilizers having a molecular weight of 600 or less and a molecular weight of 1000 or more are added together as the HALS type light stabilizer for the following reason. Normally, heavy anticorrosion coatings are often applied in a thickness of about 1 to 3 mm, but UV deterioration proceeds from the surface. For this reason, it can be said that an agent that easily diffuses from the inside to the surface is effective. A hindered piperidine-based light stabilizer having a molecular weight of 600 or less has a small molecular size and is easily diffused, and therefore, very effectively prevents deterioration in the initial stage of exposure. However, the hindered piperidine-based light stabilizer having a high diffusion rate and a molecular weight of 600 or less also has a property that it easily escapes outside the polyethylene resin-coated system due to elution or the like. For this reason, the initial deterioration prevention effect is very high, but there is a problem that the long-term performance is poor. On the other hand, hindered piperidine-based light stabilizers having a molecular weight of 1000 or more have a low diffusion rate, so that the effect of preventing the surface degradation from being diffused from inside cannot be expected in the short term,
Due to the property that it is difficult to escape, the deterioration prevention effect lasts,
Long-term degradation can be prevented.

Therefore, by adding two or more hindered piperidine-based light stabilizers having a molecular weight of 600 or less and a molecular weight of 1000 or more, respectively, a low molecular weight light stabilizer in the initial stage and a high molecular weight Each of the light stabilizers exhibits an effect of preventing deterioration, and can provide long-term weather resistance with a small amount of addition. Here, the addition amount of each is set to 0.05 parts by weight or more with respect to 100 parts by weight of the polyethylene resin, because if less than 0.05 parts by weight, the effect of preventing deterioration is reduced.

As the hindered piperidine light stabilizer having a molecular weight of 600 or less, bis (2,2,6,6-tetramethyl-4-)
Piperidinyl) sebacate (molecular weight 480), bis (N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (molecular weight 508) and the like. Examples of hindered piperidine-based light stabilizers having a molecular weight of 1,000 or more include poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-] which is an oligomer type HALS. 2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino]
Hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) iminol]] (CHIMASSORB 944 manufactured by Ciba-Geigy)
LD; molecular weight 2500 or more) or HALS having a polyester-bonded system of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and succinic acid as a main component (TINUVIN 622LD manufactured by Ciba-Geigy; molecular weight 3000 or more) ), But other than these can also be used.

The amount of the UV absorber added was polyethylene 100
The reason why the content is set to 0.05 parts by weight or more with respect to parts by weight is that if less than 0.05 parts by weight, the effect of preventing deterioration becomes insufficient. Useful UV absorbers include benzotriazoles represented by 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole and 2-hydroxy-4-methoxybenzophenone. Benzophenone, benzoate represented by 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4-hydroxybenzoate, ethyl-2-cyano-3,3-diphenylacrylate Any known ultraviolet absorber such as a cyanoacrylate-based agent may be used, and is not particularly limited.

The upper limit of the amount of these deterioration inhibitors is not particularly limited, but in any case, the amount is sufficient within several times the above lower limit. Excessive addition of the degradation inhibitor not only impairs the economics of the product, but also in some cases causes the degradation inhibitor to bleed out, leading to degradation in quality. The total amount of the deterioration inhibitor added is 3 parts per 100 parts by weight of polyethylene.
It is preferably at most 2 parts by weight, particularly preferably at most 2 parts by weight.

When the colored polyethylene resin containing the above-mentioned deterioration inhibitor used in the present invention is produced, the coloring pigment is incorporated in the polyethylene resin in an amount of 3 to 50% by weight and one or more kinds of the deterioration inhibitor in total. One or more master batches containing about 1 to 20% by weight are prepared, and the master batch and a polyethylene resin containing no deterioration inhibitor or pigment are blended in a predetermined ratio to form a colored polyethylene resin composition. Preparation of a product is easy to obtain a homogeneous composition,
It is economically advantageous. If the amount of the additive in the masterbatch is too large, it becomes difficult to produce a uniform masterbatch.

As the color pigment for coloring the polyethylene resin, any of known organic or inorganic pigments may be used. Specifically, organic pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, dioxazine-based, perinone-based, quinophthalone-based, and perylene-based pigments, ultramarine, titanium dioxide, titanium yellow, iron oxide ( Inorganic pigments such as stalks, chromium oxide and carbon black can be used. The compounding amount of the color pigment may be an amount sufficient for coloring, and cannot be specified because it varies depending on the kind of the pigment. However, it is generally in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the polyethylene resin. . In addition to the color pigment, one or more known additives such as extender pigment, rust preventive pigment, dispersant, softener, and flame retardant may be further added.

The colored polyethylene resin composition containing the above-mentioned anti-deterioration agent used in the present invention exhibits the intended long-term weather resistance of about 40 years without containing carbon black. A long-term weatherable polyethylene resin composition which can be colored in any of the following colors is obtained. The polyethylene resin-coated material of the present invention is produced by coating this composition on steel or other base material, for example, by the method described below. The coating of the polyethylene resin may be applied only to the surface of the steel material requiring corrosion protection, and it is not necessary to cover the entire surface.

Regarding the method of coating the steel material with the polyethylene resin, the following method is possible irrespective of the shape of the steel material. A: a method based on a melt extrusion method, B: a method based on an electrostatic powder coating method, C: a method based on a fluidized immersion method, D: a method based on a thermal spraying method, E: sheet lamination Method based method.

In each of the methods A to D, as described above, after the surface is cleaned by pickling or blasting, the steel surface preheated to about 120 to 300 ° C. by an appropriate heating means such as induction heating is applied to the surface. After coating a thin layer of an adhesive resin (eg, maleic anhydride-modified polyethylene resin) by any of the methods A to D,
While the adhesive resin is still in the molten state, the coating is carried out by coating the colored polyethylene resin composition containing the anti-degradation agent, which is a coating material, on the adhesive layer also in any one of the above-mentioned methods A to D. it can. Although the adhesive resin and the colored polyethylene resin composition can be coated by different methods,
Coating in the same manner will usually be easier to manufacture.

More specifically, the coating method A is carried out by extruding a molten resin on a preheated steel surface from an appropriate extruder into a film or sheet. B
The coating method is carried out by spraying a powdered resin charged with static electricity from a spray gun onto a grounded preheated steel material and, if necessary, heating the resin to a temperature equal to or higher than the melting point of the resin to smooth the coating surface. . The coating method of C is performed by fluidizing the powder resin, immersing the preheated steel material in the fluidized bed of the powder resin, and further heating the resin to a temperature equal to or higher than the melting point of the resin, if necessary. The coating method of D is performed by melting the powder resin with a flame of a thermal spray gun and spraying it on the surface of the preheated steel material.

In the laminating method of E, a multi-layer sheet composed of an adhesive layer and a colored polyethylene resin layer is formed by a two-layer coextrusion method or an extrusion laminating method. Simultaneously with or after the formation of the sheet, the laminate is applied to the cleaned and preheated steel surface. Alternatively, a film of an adhesive resin and a sheet of a colored polyethylene resin composition containing a deterioration inhibitor are separately prepared, and these two layers are separately prepared.
Alternatively, a method is also possible in which the two layers are pre-laminated and then laminated on the cleaned and preheated steel surface so that the adhesive layer is on the inside.

[0039]

Next, an embodiment will be described. After the surface of steel sheet pile (Sumitomo Metal Industries; SKSP-II type) was adjusted (Sa: 2.5 or more) by shot blasting, the chromium deposition amount was 200 mg /
coating type chromate bath such that m ² (Kansai Ltd. Paint;
Chromate treatment was performed with Cosmer 100). An epoxy resin primer (Nippon Paint; N
o.66 primer) was applied so as to have a dry film thickness of 30 μm, and the steel material was heated to 190 ° C. using an induction heating device to bake the primer and preheat the steel material.

On the other hand, the colored polyethylene resin composition to be coated is a medium-to-low pressure polyethylene (manufactured by Showa Denko; Shorex S4002 EX, MFR 0.20 g / 10 min, density 0.935 g / cc, all measured according to JIS K 7210). ) Were combined with 2 to 4 kinds of pigments shown in Table 1 (addition amounts of each pigment were almost the same) in total of 2% by weight, and some of the following degradation inhibitors (a) to (i). It was prepared by blending.

[0041]

[Table 1]

Deterioration inhibitor used (a) 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy}-
1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane (one-sided hindered phenolic antioxidant; ADEKA argus, MARK AO80) (b) 4,4'- Thiobis (3-methyl-6-t-butylphenol) (one-sided hindered phenol-based antioxidant; Sumitomo Chemical Co., Ltd., Sumilizer WX-R) (c) tetrakis- [methylene-3- (3 ′, 5′-t- Butyl-4'-hydroxyphenyl) propionate] methane
(Both hindered phenolic antioxidants; IRGANOX 1010, manufactured by Ciba Geigy) (for comparison) (d) Pentaerythritol-tetrakis (β-lauryl-thiopropionate) (sulfur antioxidant containing ester bond; ADEKA ARGAS (MARK AO412S) (e) 2-mercaptobenzimidazole (sulfur antioxidant without ester bond; Sumitomo Chemical, Sumilizer
MB) (for comparison) (f) Bis (2,2,6,6-tetramethyl-4-piperidinyl)
Sebacate (hindered piperidine light stabilizer having a molecular weight of 480; TINUVIN 770, manufactured by Ciba Geigy) (g) Poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine- 2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene
[(2,2,6,6-tetramethyl-4-piperidyl) iminol]] (Hindered piperidine-based light stabilizer having a molecular weight of 2,500 or more; CHIMASSORB944LD manufactured by Ciba Geigy) (h) (2,2,6,6-tetrahedral) (Methyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate (a hindered piperidine-based light stabilizer having a molecular weight of 900; ADEKA ARGAS, MARK LO-67) (for comparison) (i) 2 -(3'-t-butyl-5'-methyl-2'-hydroxyphenyl) -5-chlorobenzotriazole (ultraviolet absorber; manufactured by Ciba Geigy, TINUVIN 327) Compounding amount of deterioration inhibitor (weight based on 100 parts by weight of resin) Part)
Are as shown in Table 2, and the total amount of the deterioration inhibitor was 0.3 parts by weight except for Comparative Example 15 (Comparative Example 15
0.33 parts by weight). The actual preparation of the resin composition was performed by preparing a master batch in which a pigment and a deterioration inhibitor were mixed at a high concentration with a polyethylene resin, and mixing this with an unadded polyethylene resin.

The colored polyethylene resin composition containing the deterioration inhibitor and the maleic anhydride-modified polyethylene resin (Mitsui Petrochemical; Admer) as an adhesive were co-extruded in two layers to form a multilayer polyethylene sheet having a width of 900 mm. I got The thickness of this sheet was 0.3 mm for the adhesive layer and 2.2 mm for the colored polyethylene resin layer. After heating the sheet to about 80 ° C with an infrared heater, the modified polyethylene resin of the adhesive layer is fused and coated while rolling the steel sheet pile with a press roll on the convex part of the preheated steel sheet pile, and then coating the colored polyethylene sheet. A coated steel sheet pile was obtained.

Using a 150 × 70 mm steel sheet cut out from the coated portion of the polyethylene-coated steel sheet pile as a test piece, an accelerated weathering test (black panel temperature: 63 ° C.) using a sunshine weather meter (WOM) manufactured by Suga Test Machine was performed at a maximum of 8,000.
Performed until time. 8000 hours of WOM weather test (WOM80
(00 hours) is equivalent to about 40 years of ultraviolet irradiation in a real environment.

Every 1000 hours of irradiation, a polyethylene resin film was cut out from the test piece, a tensile test was performed, and the elongation retention with respect to the initial tensile elongation was measured. In general, when the elongation retention is 50% or less, it is considered to be in a deteriorated state.
This time was taken as the degradation start time. In the evaluation, those having an elongation retention of 50% or more even after 8000 hours of the accelerated weathering test were evaluated as good (○), and those having an elongation retention of less than 50% were evaluated as poor (x). The test results are also shown in Table 2.

[0046]

[Table 2]

In Examples 1 to 8 according to the present invention, the tensile elongation retention hardly decreased even after 8,000 hours of WOM, and the weather resistance was good. That is, the resin-coated steel material of the present invention has a long-term weather resistance of at least 40 years. Comparative Example 1
In Nos. To 14, deterioration was shown in less than 8000 hours, even though the total amount of the deterioration inhibitor was the same as that in the example. Further, in Comparative Example 15, the life was shortened as a result of the antagonism between the sulfur-based antioxidant and HALS, although the total amount of the deterioration inhibitor was increased as compared with Comparative Example 4. .

From the above, based on 100 parts by weight of polyethylene, 0.05% by weight or more of one-sided hindered phenolic antioxidant and 30% of the amount of one-sided hindered phenolic antioxidant having an ester bond-containing sulfur-based antioxidant were added. More than 70%,
Hindered piperidine light stabilizer with a molecular weight of 600 or less 0.05
5 parts by weight or more, hindered piperidine-based light stabilizer with a molecular weight of 1000 or more, 0.05 parts by weight or more, and ultraviolet absorber 0.05 parts by weight or more. It can be seen that the effect is obtained, and long-term weather resistance of about 40 years can be secured by adding a small amount of a deterioration inhibitor.

[0049]

As described above, the colored polyethylene-coated material of the present invention comprises a polyethylene resin layer, in addition to a colored pigment, a one-sided hindered phenolic antioxidant and a sulfur-based antioxidant having an ester bond. Since the two types of hindered piperidine-based light stabilizers having a specific molecular weight range and the ultraviolet absorber are blended in a certain amount or more, respectively, the synergistic effect of these deterioration inhibitors prevents carbon black from being blended. Even, it shows long-term weather resistance for about 40 years. In addition, since the addition amount of these deterioration inhibitors may be small, the corrosion resistance, impact resistance and economy of the coating material are not impaired. This makes it possible to use polyethylene resin-coated materials that are colored freely according to the usage environment outdoors for more than 40 years, expanding the range of use of various materials, including steel materials such as steel sheet piles. And the service life is extended.

Claims (1)

(57) [Claims] [Claim 1] 100 parts by weight of polyethylene resin,
One-sided hindered phenolic antioxidant 0.05 parts by weight or more,
A sulfur-based antioxidant having an ester bond is used in an amount of 30% or more and 70% or less of the amount of one-sided hindered phenolic antioxidant, a hindered piperidine-based light stabilizer having a molecular weight of 600 or less 0.05 parts by weight or more, and a hindered having a molecular weight of 1000 or more A colored polyethylene coating material, characterized in that the surface thereof is coated with a resin layer comprising a colored polyethylene composition containing 0.05 parts by weight or more of a piperidine-based light stabilizer and 0.05 parts by weight or more of an ultraviolet absorber.